Classifier



J. V. SLADE July 4, 1933.

CLASSIFIER Filed NOV. .18 1930 2 Sheets-Sheet 1 INVENTOR JAMES KSLADEATTORNEY July 4,1933. SLADE v 1,916,392

.CLASSIFIER Filed Nov. 18 1950 2 Sheets-Sheet 2 Zlwuentot JAMES MSLADE.ones.

Patented July 4, 1933 UNITED STATES PATENT OFFICE,

JAMES V. SLADE, 0F LARCHMONT, NEW YORK, ASSIGNOR, BY MESNE ASSIGNMENTS,TO THE DORE COMPANY, INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARECLASSIFIER Application filed November 18, 1930. Serial No. 496,403.

This invention relates to classifiers, and more particularly to thattype of classifier intended to perform a classifying or sortingoperation of particles of mixed sizes or different specific gravities orboth by permitting the particles or part of them to settle in a fluid.The general type of classifier forming the basis of the invention isshown and described in United States Letters Patent 1,292,237 issuedJanuary 21, 1919, to

For better comprehension of the invention and realization of theproblems involved and solutions presented hereinafter, attention isfirst invited to several basic principles affecting materialclassification.

If a mixture of various particles or particles of different specificgravity be introduced in a fluid, the larger or heavier will sink morerapidly than the finer or lighter This action will be referred to asclassification under free settling conditions. Agitation of the solutionwill tend to keep the finer particles in suspension, but where theagitation is not too vigorous the coarser particles will continue tosettle. If the settling particles be subjected to an upflow or risingcurrent the settling velocities of the particles will be reduced inproportion to the intensity of the upflow. By regulating the upflow, avery exact division can be made between the finer particles which willnot sink because of the upward velocity of the fluid and the coarserparticles which do sink.

This action is termed classification under hindered settling conditions.In the application of this principle to classifiers of the type shown insaid Patent 1,292,237, the upflow of the fluid is produced from asecondary compartment to a primary chamber through a constrictedopening. By passing the upflow through the constricted opening, thevelocity is greatest at the opening, so that the finer particles are notonly carried up into the primary chamber but are retained in suspensiontherein so as to ultimately pass over a weir provided for exit of thefluid from the primary chamber. The size of the particles overflowedwith this outgoing fluid is a function of the settling velocities ofsuch particles. Collaterally, the size, quantity and character of theparticles in the overflow are functions of the disturbing influencesaffecting both the free settling conditions and the hindered settlingconditions in the primary chamber or bowl.

One of the problems affecting proper and efficient classification is theirregularity of or spasmodic introduction into the bowl of material tobe classified. The present invention seeks to improve the proper andeflicient classification 'by obtaining an equalization of introductionof the materials, that is, attempts to approach as nearly as possiblethe ideal condition of a steady flow. Again, the invention seeks toobtain a flow of entering material with minimum ripple and disturbmgcurrents and yet with the material introduced atthe surface of the fluidso as to have maximum depth for settling purposes.

A further difficulty with the usual hydromechanical classifiers arisesfrom the fact that the primary chamber permits particles of certainintermediate size to settle and pass to the secondary compartment wherethat size may not be permitted to settle and is returned forreclassification. As a result, the density of the fluid in the vicinityof the constriction builds up, thereby alterin the hindered settlingcondition and the up ow, not only causing oversize particles to escapewith the outflow over the weir from the primary chamber, but alsotending to clog the rake. The invention looks to the provision of astructure properly balancing the settling conditions of the two chambersand regulating the upflow from the secondary compartment to the primarychamber.

With the specific problems mentioned above in view and with the objectsalready stated in mind, with'other objects and ad vantages as may moreclearly appear in the following description, one embodiment of theinvention is illustrated in the accompanying drawings, in which likenumerals of reference indicate (similar parts throughout the severalviews and in which Figure 1 is a plan of a classifier constructed In thespecific embodiment of the invention illustrated in said drawings, thebasic construction shown provides two settling tanks identified asprimary settling chamber 1, and secondary settling compartment 2,respectively, the two being connected by a constricted opening 3. Bothtanks have mechanical rakes, the rake or sweep 4 in the primary chamber1 impelling the settled material toward the constricted opening 3,whereas the bladed rake 5 in the secondary compartment 2, impels thesettled material therein up the inclined bottom of compartment 2 andinto any suitable receiving means. This general assembly just describedis old in the art.

As the secondary compartment and associated parts are in most partlikewise old in the art, a brief outline thereof will suflice herein.Secondary compartment 2 is in the form of an inclined trough in which amechanically operated reciprocating bladed rake 5 actuates settledmaterial upwardly with a step by step motion. The rake is carried by twohangers, 6, 7, one, as 6, near the discharge end and the other, 7,toward the lower end, both hangers being supported by interconnectedbell cranks 8, 9 respectively, the upper one, 8, of which has a rockerlever 10 depending therefrom for actuation by a cam 11 driven throughsuitable reduction gears by a motor 12. This structure obtains anoffsetting movement of the entire rake toward and away from the bottomof the trough. Reciprocation of the rake is obtained by a crank-operatedpitman 13, this reciprocal movement, combined with the offsettingmovement, resulting in an orbital movement by which the materialssettling on the bottom of the trough will be intermittently draggedup'the incline with astep by step motion.

The primary chamber 1 may also include certain parts as heretofore usedincluding a circular bowl construction with a bottom sloping downwardlytoward the center wherein is provided the constricted opening 3 to thesecondary compartment directly below. Above the bowl or chamber 1, is asuperstructure 14, upon which is carried a motor 15 which actuates alongitudinally adjustable vertical shaft 16 through suitable drivingconnections. This shaft is axially disposed with respect to the bowl andcarries the rake 4 at the lower part of the shaft,

- thereby rotating said rake by virtue of direct connection between saidparts.

Heretofore it has been common practice to construct the rakes with thescrapers all of sub tantially the same height, in other words, with thetop of the rake substantially parallel to the bottom of the tank alongthe line where the rake overlies the tank bottom, and below the surfacelevel of the fluid in the bowl. In the present invention, however, therake provides rake arms 17, not only perpendicular to the shaft butpositioned above the normal surface level of the fluid in the chamher.As is usual with devices of this type, the rake has blades or scrapers18 at acute angles with respect to radial planes from the shaft, saidscrapers having bottom edges closely adjacent to the bottom of the bowlso as to scrape the settled material toward the center of the bowl. Inthe present showing. the blades or scrapers nearest the middle of thebowl are of greater height than the blades nearest the outer edge of thebowl, the intervening blades from the innermost to the outermost beingprogressively shorter than the next preceding blade. In other words,blades are proportionate in height to the depth of the fluid in the bowlthereby obtaining greater agitation where the fluid is the deepest andless agitation where the fluid is more shallow. The agitation, thuspropoi'tionate to the depth of the fluid, is more evenly distributed asa result of which the finer particles are kept in suspension throughoutthe content of the bowl and excessive agitation near the periphery ofthe bowl or surface of the solution is avoided. The construction shownprovides blades of such length that all of the upper edges of the bladesare in a common plane, and are of such a height that the plane of theupper edges is below the surface level of the solution in the bowl.

The blades 18 are each carried by a bracket 19 depending from the arm 17of the rake. Preferably there is a separate bracket for each blade, andobviously part of the bracket is abovethe solution for attachment to thearm of the rake whereas the lower part of each bracket is below thesurface of the solution for carrying the blade. The bracket willaccordingly obtain a restricted evenly distributed slight surfaceagitation of the solution, this feature being deemed an importantfeature of the present invention, and it is for this reason that it ispreferable to utilize a separate bracket for each blade. It is to benoted that the brackets are each shown to be a short length of I-beamconstruction providing upper and lower flanges and a vertical webportion. The length of the I-beam brackets are arranged transverse tothe rake arms, each bracket preferably having a length substantially thewidth of said arm. This construction makes the webbing of the bracketstangential to the circle or orbit of revolution thereof and thereforethe surface strata of the solution will be out only by the edge of thebracket and will not suffer any material lateral displacement. Thecutting action is found to obtain a very desirable although relativelyslight agitation in the surface strata. By reference to the drawings itwill be observed that the solution is permitted to escape or have itsoutflow around the entire circumference of the bowl over acircumferential weir 20. The height of this weir is in a plane whichintersects the webbing of the several brackets. The escaping solutionpassing over the weir enters a spillway or launder 21 which slopesdownwardly around the bowl toward one end of the same so as to dischargethe solution through a. single outlet 22 as will be understood by thosel illed in the art.

Another important feature is the vertical adjustment of the rake arm 17by means of the wheel nut 46 and the threaded end of the ve;t-ical shaft16. This adjustment permits variation of the depth of submergence of therake blades 18 to a considerable extent. Such adjustment is permissiblewithout bringing the rakes above the liquid level and depends upon thevertical length of the supporting and surface cutting elements 19.

It is further to be noted that the length of the surface cuttingelements 19 in the,

general direction of travel, may be large or small, according to thedesired length of the intermittent periods of interruption of outwardflow of material near the liquid level.

As shown more clearly in Fig. 5, the weir 20 is rendered adjustable inheight by constructing it in the form of a band of rubber belting fittedtightly around the rim of the bowl shaped settling tank 1 and laced atthe meeting ends as indicated at 41. The strip of belting is preferablyfirst cut to a size to fit snugly around the'rim of the chamber 1, thenlaced tightly together at its ends to form a continuous band which isstretched over the rim and tapped down to the required elevation. It isthus possible to accurately level the edge of the weir and adjust itsheight independently of the other parts of the mechainsm.

Entry of the material under treatment is obtained substantially at thetop middle part of the bowl, the same being shown as introduced through.a supply passage 23 to an equalizing or feed well 24. Said equalizingwell is shown circular and the supply passage 23 is shown introducedthereinto at one side in a substantially tangential direction so thatthe entering material will have a swirling action to immediately spreaditself entirely around the equalizing well. The bottom of the well isperforated, as at 25, for retarded escape of the material therethroughonto a distributing plate 26 positioned thereunder. This distributingplate is shown as having a middle portion 27 which is at least as largein diameter as the well and shoulders off, as at 28. at its periphery toa lower level providing a peripheral flange or apron 29 in aplaneparallel to the said middle portion 27. The specific construction shownis such that the middle portion 27 of the distributing plate is carriedupon the upper edges of the radial rake arms and the edge shoulder 28 isa circular band properly cut away to pass the said rake arms andextending downwardly below the said arms and also below the plane of theweir 20, thus positioning the apron 29 below the surface of the solutionin the bowl. However, this submersion of said apron 29 is not to anygreat depth and preferably is only very slightly below the surface.Spaced radially outwardly from the shoulder and extending around thesame is an upstanding entry Weir 30 secured to the outwardly directedapron and thereby providing in association with the said apron 29 andshoulder 28 of the central plate an annular launder 31 from which thematerial to be treated can escape around the entire periphery over theentry weir 30.

Above the launder 31 is positioned a baffie ring 32, this ring beingopposite the raised or central portion of the plate and dependingpartway down the shoulder 28 in spaced relation therefrom thus confiningthe material in its passage from the equalizing well 24 to the launder31 and preventing escape of said material in any direction except overthe entry weir. By this construction the entering material is spreadover a considerable area and enters the bowl at a material distance fromthe center thereof so as not to interfere in any way with the up-flowthrough the constricted opening 3 in the bottom and center of the bowl.As shown, the apron 29 extends outwardly beyond the position of the weirso that the flow of the entering material will have a direct tendency tomove the same radially outward and will avoid down currents fromspilling over the weir directly into the bowl. The settling particlesfrom the en tering material obviously will come to the bottom of thebowl a distance from the constricted opening 3 and therefore thedownflow of particles through the constricted opening will be at theedges of the constricted opening and none in the middle of the opening,thus giving the upfiow free passage in the area beneath the distributingplate. This fiow is caused mainly by the back wash supplied to thesecondary compartment through conduit 45 from a suitable sourceofsupply.

As shown in Figures 2, 3 and 4 more particularly, the constrictedopening 3 of the bowl is at the lowermost point of the bowl, it beingnoted that the bottom of the bowl tapers toward its center as a resultof which said constricted opening is both at the middle and lowest partof the bowl. fier to function properly is frequently due to accumulationof material in the secondary Failure of a classiv compartment below thesaid constricted open- Y However, much of this material if returned tothe primary chamber will pass over the overflow or discharge weir. It istherefore a fea ture of the present invention to obtain means foradjustably regulating the upflow of material or the velocity of theupflow. By such a regulation, much material will be kept in the primarychamber which belongs there but which is so near the critical size orspecific gravity as to be influenced by the down current. In the presentinvention it is preferred to provide means to regulate the upflowvelocity by adjusting the size of this constricted opening. For thispurpose suitable guides 33 are. used at opposite sides of the saidopening for receiving horizontal gates 34 slidably mounted in saidguides. Any suitable operatin g means may be provided to both slide thegates and to hold them in adjusted position. Illustrative of thisfeature of the invention, is shown a slide bar 35 for each gateconnected at its inner end, as at 36, to the gate and passing outwardlythrough the side of the secondary compartment 2 through an appropriatestufling box 37. This arrangement enables the slide bar 35 to bereciprocated without loss of any of the fluid contents of thecompartment. The outer end of the slide bar 35 is screw threaded as at38, and a handwheel 39 is carried upon this threaded end of the slidebar. By suitably anchoring the hand-wheel 39 against movement in adirection longitudinally of the slide bar, but permitting said wheel tobe rotated, the said rotation will obviously actuate the slide barlongitudinally depending which way the hand-wheel is turned. Any desiredmeans may be employed for thus anchoring the hand-wheel, as by providinga peripheral groove in its hub and providing an inwardly projecting partfrom the bar support 40 to engage in the groove as will be understood bythose skilled in the art.

Obviously detail changes and modifications may be made in theconstruction and use of the classifier, and it is not to be understoodthat the invention is restricted to the exact details of construction ormodes of operation herein described except as set forth in the followingclaims when construed in the light of the prior art.

Having thus described the invention, I claim 1. In a classifier, meansfor equalizing flow of material to the classifier, a distributing platefor receiving the materials, said plate having an edge over which thematerials may fall into the classifier, a battle opposite the said edgeof the plate and spaced therefrom and an apron below said edge of theplate for receiving the material and preventing the falling materialfrom setting up a downward current in the classifier.

2. In a classifier, means for equalizing flow of material to'theclassifier, a distributing plate for receiving the materials, said platehaving an edge over which the materials may fall intothe classifier, abaflie opposite the said edge of the plate and spaced therefrom, anapron below said edge of the plate for receiving the material andpreventing the falling material from setting up a downward current inthe classifier, and a weir on said apron over which the material mayflow in a direction toward the periphery of the classifier.

3. In a classifier, means for equalizing flow of material to theclassifier, a distributing plate for receiving the materials, said platehaving an edge over which the materials may fall into the classifier, abafiie opposite the said edge of the plate and spaced therefrom, anapron below said edge of the plate for receiving the material andpreventing the falling material from setting up a downward current inthe classifier, and a weir on said apron over which the material mayflow in a direction toward the periphery of the classifier, said plateand apron having a shoulder connection for preventing flow of materialin any direction except over the weir.

4. In a classifier, means for equalizing flow (if-material to theclassifier, a distributing plate for receiving the materials, said platehaving an edge over which the materials may fall into the classifier, abaffle opposite the said edge of the plate and spaced therefrom. anapron below said edge of the plate for receiving the material andpreventing the falling material from setting up a downward current inthe classifier, and a weir on said apron over which the material mayflow in a direction toward the periphery of the classifier, said apronextending beyond the weir so as to prevent down currents by the materialpassing over the weir.

5. Classifying apparatus provided with substantially circular feed well,a feed inlet conduit arranged tangentially thereto whereby feed issuingfrom said conduit is caused to swirl circumferentially in said feedwcll,

and a plurality of outlets from said feedwell arranged at right anglesto the plane of the swirling feed.

6. Classifying apparatus having a secondary raking classifiercompartment, a primary sedimentation chamber superposed thereon andcommunicating therewith, rakes for conveying solids settling in saidchamber to said compartment, and means for rendering uniform the mixtureoverflowing from said chamber comprising a combined weir partly rigidand partly flexible.

7. Apparatus according-to claim 6 in which the flexible part of saidcombined weir is adjustably held to said rigid part by tension.

In testimony whereof I aflix my signature.

JAMES v. SLADE.

